How to access projected 3d tracks of the camera solver?

Question

For further reconstruction of a shot, I'd like to access the 3d location of the projected tracks by the camera solver constraint in the 3d View for all frames via python.

While searching through the Datablocks I've only found a read only bundle attribute per track: bpy.data.movieclips["clip_name"].tracking.tracks["track_name"].bundle, but unfortunately the given coordinates are totally off:

Is there any way to access the properties of the 3d tracks at the moment?

Answer 1

Copy matrix_world uninfluenced by "Camera Solver" constraint, ie set constraint influence to 0, set the frame to the first frame of the simulation, save a matrix_world copy, then reset the influence.

The track positions are mworldcopy * Track.bundle

Camera tracking points in red, object tracking points in green, resultant object tracking points in yellow.

import bpy

from sound_drivers.BGL_draw_visualiser import BGLWidget

context = bpy.context
scene = context.scene
scene.frame_set(1)
camera = cam = scene.camera
cam_const = cam.constraints[0]
cam_const.influence = 0
mw = cam.matrix_world.copy()
cam_const.influence = 1

class ShowTracks(BGLWidget):
    def draw_region(self, context):
        clip = context.scene.active_clip
        tracking = clip.tracking                
        tracking_object = clip.tracking.objects.active

        # match to object tracking
        # from bl_operators/clip.py
        if camera:
            reconstruction = tracking_object.reconstruction
            framenr = scene.frame_current - clip.frame_start + 1
            reconstructed_matrix = reconstruction.cameras.matrix_from_frame(framenr)
            matrix = camera.matrix_world * reconstructed_matrix.inverted()

        else:
            return

        tracks = tracking.objects

        # track points in global space current frame         
        pts = [matrix  * t.bundle for t in tracks['Object'].tracks]    
        pts = self.points3d_points2d(context, pts)
        self.draw_points(pts, lw=2, color=(1, 1, 0, 1))

        # tracking data 
        pts = [mw * t.bundle for t in tracks['Camera'].tracks]
        pts = self.points3d_points2d(context, pts)
        self.draw_points(pts, lw=1, color=(1, 0, 0, 1))

        pts = [mw * t.bundle for t in tracks['Object'].tracks]
        pts = self.points3d_points2d(context, pts)
        self.draw_points(pts, lw=1, color=(0, 1, 0, 1))

v = ShowTracks(None, bpy.context, bpy.types.SpaceView3D)